A cluster is a type of parallel or distributed processing system, which consists of a collection of interconnected stand-alone computers cooperatively working together as a single, integrated computing resource. This cluster of computers shares common network characteristics like the same namespace and it is available to other computers on the network as a single resource. These computers are linked together using high-speed network interfaces between themselves and the actual binding together of the all the individual computers in the cluster is performed by the operating system and the software used. he recent advances in high-speed networks and improved microprocessor performance are making clusters or networks of workstations an appealing vehicle for cost effective parallel computing. Clusters built using commodity hardware and software components are playing a major role in redefining the concept of supercomputing. Clustering using Commercial Off The Shelf (COTS) is way cheaper than buying specialized machines for computing. Cluster computing has emerged as a result of the convergence of several trends, including the availability of inexpensive high performance microprocessors and high-speed networks, and the development of standard software tools for high performance distributed computing.As processing power becomes available, applications which require enormous amount of processing, like weather modeling are becoming more common place requiring the high performance computing provided by Clusters.

Components of a Cluster

The main components of a cluster are the Personal Computer and the interconnection network. The computer can be built out of Commercial off the shelf components (COTS) and is available economically.

The interconnection network can be either an ATM ring (Asynchronous Transfer Mode) which guarantees a fast and effective connection, or a Fast Ethernet connection which is commonly available now. Gigabit Ethernet which provides speeds up to 1000Mbps,or Myrinet a commercial interconnection network with high speed and reduced latency are viable options.

But for high-end scientific clustering , there are a variety of network interface cards designed specifically for clustering.

Those include Myricom's Myrinet, Giganet's cLAN and the IEEE 1596 standard Scalable Coherent Interface (SCI). Those cards' function is not only to provide high bandwidth between the nodes of the cluster but also to reduce the latency (the time it takes to send messages). Those latencies are crucial to exchanging state information between the nodes to keep their operations synchronized